DE1595693B2 - Process for the preparation of aqueous polymer dispersions - Google Patents

Description

The process according to the invention, in which, in general, the light-active nonionic Emulsifiers are used in amounts of 1 to 15%, based on the weight of the monomer or monomers results in dispersions in which both the water-soluble emulsifier and the polymer content are not networked. Unexposed films produced from the dispersions are completely in the Soluble in common organic solvents. Furthermore, the films show one of many uses unfavorable high water sensitivity.

However, if films or coatings are obtained from the dispersions prepared according to the invention or paints are irradiated with light having a wavelength of 2000 to 8000 Å, crosslinked products are obtained. As a result of the crosslinking process, the hydrophobic part becomes the light-active nonionic Emulsifiers are firmly bound to the latex particles and the emulsifier can no longer be washed out, Surprisingly, the crosslinking process also releases any protective colloid content that may be present firmly bound, so that this too becomes one of the dispersion after appropriate exposure z. B. formed film or coating can no longer be extracted with water. From the invention The exposed films or coatings obtained show, in addition to increased solvent resistance, dispersions produced a number of other decisive advantages. While z. B. an unirradiated one The film is severely attacked in a short time by the action of alkali, swells up and returns to its original state If a film that has been crosslinked by light loses its shape completely, it can easily last 14 days Can be exposed to alkali at 70 ° C without changing its appearance or shape. Farther the tear resistance is increased by the irradiation, and in addition, it is in the case of pigmented films the pigment is no longer washed out to the same extent as with uncrosslinked pigmented films.

The dispersions are in the presence of the usual water-soluble polymerization catalysts, for. B. Salts of persulphuric acid or hydrogen peroxide and water-soluble derivatives of hydrogen peroxide or water-soluble azo compounds. Furthermore, those for emulsion polymerization can also be used common redox systems are used.

In addition to the nonionic, light-active emulsifiers to be used according to the invention Compounds additionally known nonionic, anionic and cationic emulsifiers and combinations of these emulsifiers can be used.

High molecular weight compounds such as polyvinyl alcohol, polyvinylpyrrolidone, Cellulose derivatives, polyacrylamide, polymethacrylamide are used.

In order to achieve an even better stabilization of the dispersion, unsaturated carboxylic acids such as Acrylic and methacrylic acid or vinylsulphonic acid and vinylphosphonic acid or their alkali salts are also polymerized will.

The polymerization is generally carried out at a pH between 3 and 9 and at temperatures of 20 to 90 ° C carried out.

The dispersions prepared according to the invention can, for. B. as a pigment binder for film and Paper coating, used for the production of self-gloss emulsions and textile finishes will. The parts mentioned in the following examples are parts by weight.

B e i s ρ i e 1 1

In a glass vessel equipped with a thermometer, stirrer, reflux condenser and dropping funnel the solution of 12 parts of an oxethylation product from one mole of p-oxybenzophenone with 14 moles of ethylene oxide, 0.15 part of sodium vinylsulfonate, 0.25 part of sodium acetate, 1.5 parts of Poly-N-vinyl-2-pyrrolidone and 0.42 parts of potassium persulfate heated to 80 ° C. in 109 parts of water.

The monomer mixture of 67 parts of vinyl acetate and 33 parts of vinyl ester of a mixture of aliphatic carboxylic acids branched in the α-position and having 9 to 11 carbon atoms (boiling point: 205 to 262 ° C. at 760 mm Hg) is then added dropwise over 3 hours. After the feed has ended, the solution of 0.1 part of potassium persulfate in 5 parts of water is added and the mixture is heated for 2 hours. It is then cooled to room temperature.
A medium-sized, coagulate-free, low-temperature stable and pigment-compatible dispersion of about is obtained

"- 50% solids content and a viscosity (Höppler viscometer, 20 ° C) of 0.8 P. The dispersion dries to a clear, homogeneous and elastic film that is completely soluble in the usual organic solvents Such a film is about 6%, based on the dry content. However, if a film (0.8 mm thick) is irradiated with either a UV lamp, a xenon lamp or daylight, crosslinking takes place and thus the one which is soluble in organic solvents If, for example, a film (0.8 mm) is irradiated with a xenon lamp for 7 hours and then treated with boiling water for 4 hours, only 1% of the water-soluble components can be dissolved out of the film Irradiation of a film for 12 hours with a xenon lamp and subsequent treatment in boiling acetone for 4 hours results in an insoluble fraction (gel fraction) of 59% Hour, xenon lamp) increases by 40% compared to that of a non-irradiated film. A non-irradiated film loses its shape due to the action of alkali, swells and disintegrates, while an irradiated film in 1 nKOH (10 days at 70 ° C.) retains its shape and appearance completely. The pigment binding power of crosslinked films is greater than that of uncrosslinked films. In the latter case, a film in acetone pigmented with white pigment (40 parts TiO ₂ , 52 parts BaS O4, 5 parts talc, 3 parts chalk) completely releases the pigment. As a result of the crosslinking, the pigment is largely retained and only slightly dissolved out.

Example 2

The dispersion is produced according to the recipe given in Example 1, but instead of the oxyethylation product from one mole of p-oxybenzophenone with 14 moles of ethylene oxide and 12 parts of an oxyethylation product from one mole of p-oxybenzophenone with 30 moles of ethylene oxide. It will a medium-sized, coagulate-free, low-temperature stable and pigment-compatible dispersion with a solids content of around 50% and a viscosity (Höppler-Viskosi-

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meter, 20 ⁰ G) of 8.7 P. The properties still 1%. The Gelähteil (for 4 hr ψ acetone) one obtained film AIIS the dispersion with respect to the irradiation after 12 hours is 46%. The tear-crosslinkability corresponds completely to the strength increased by annoying irradiation which are given in Example 1. (Xerion lamp) by 28%. The alkali resistance and before crosslinking can be removed with water 6% 5 the pigment binding power is only improved by crosslinking (7 hours irradiated ^ Xenorilamp) in the same way as the solid substance from a film, as described in Example 1.

Claims (2)

1 2 are crosslinked, and that, moreover, the dispersions have one patent claims: insufficient storage stability. Since the contained in the dispersions mentioned 1. Process for the production of aqueous, pre-crosslinked latex particles, which are harder and less free-flowing polymer dispersions are capable of emulsion polymers, the dispersions show an insufficient ization of vinyl esters, acrylic and methacrylic film-forming capacity. But it is for obtaining acid esters by themselves or in a mixture with one another, the properties listed above from Dig, if necessary together with ethylene, isobutylene, dispersions of vulnerable copolymers produced higher A-01efinen with up to 12 carbon th coatings and films are often of decisive importance Atoms, styrene, acrylonitrile, maleic acid or io meaning that crosslinking only takes place after Fumaric acid esters in the presence of the usual poly film formation begins. In addition, for many annotation catalysts, Characterized the purpose of the crosslinking is characterized by the fact that in the presence of 1 to temperature too high. 15%, based on the weight of the mono- It is also known that aqueous diners, light-active non-ionic emulsifiers 15 dispersions of homo- or copolymers herder general formula, which is characterized by increased stability excel when considering the polymerization of the or O p. / ρττ ρττ r \ \ η of the monomers in the presence of a suitable Dill * -w ^ 2 2>"spergiermittels performs It may, for example, in the R -. C - \ /. 20 use of non-ionic dispersants, ^ = f / such as alkylated aromatic oxy compounds, the are oxyethylated, 'dispersions are obtained that in which R for a methyl group or a phenyl group is characterized by high stability, good pigment compatibility or straight-chain or branched alkyl and good frost resistance. The dispersants contained in these dispersions with 1 to 18 carbon atoms have a tuated phenyl group, and in which η means a whole, often desired softening effect on the poly number of 1 to 200, optionally in merisate. However, the presence of this dispersant mixture with known emulsifiers has the disadvantage that they impart a relatively high sensitivity to water between 3 and 9 and temperatures of 20 to 30 to a film produced from the and / or protective colloids at a pH dispersion.
90 ° C polymerized. There is therefore a great need in practice 2. The method according to claim 1, characterized ge according to polymers, the dispersions of which indicates that emulsifiers of the above are storable and the films are used after drying formula in which η a whole even at room temperature under mild conditions from 4 to 60 means. 35 connections can be networked. - There has now been a method of making . aqueous polymer dispersions with improved Properties by emulsion polymerization of vinyl esters, e.g. B. Esters from vinyl alcohol and straight It is known, aqueous dispersions of homo-chain or branched aliphatic carboxylic acids and copolymers for the production of coatings, with 1 to 18 carbon atoms, acrylic and methvone Textile impregnation agents, as binders for acrylic acid esters, e.g. B. Esters from acrylic and meth paints and in numerous other areas acrylic acid with straight-chain or branched alizu use. For the usability of these dis- phatic alcohols with 1 to 18 carbon atoms, persionen in practice is important, among other things, 45 alone or in combination with each other, if necessary that they have a good film-forming ability. together with ethylene, isobutylene, higher «-Ole-Next are supposed to be used to make textile impregnations with up to 12 carbon atoms, styrene, acrylic stanchions or coatings according to the respective claims nitrile, maleic or fumaric acid esters, in counter- "in Sufficient in terms of solvent resistance, conventional polymerization catalysts were found, and paints 50 produced with the aid of the dispersions, which are characterized in that they are present good weather resistance, good solubility from 1 to 15%, based on the weight of the or Resistance to solvents and alkalis and only one of the monomers, light-active, non-ionic emulsions Show sensitivity to water. gators of the general formula It is also known that one can use aqueous dispersions of those copolymers which are still reactive 55 O _n , """" _ Groups through which a network is created, || / r ^ y ^ " included for the manufacture of coatings and r - q - <ζ ^> Can use paints. So you can z. B. aqueous \ = /
Dispersions of self-crosslinking copolymers produce when one in an aqueous emulsion derivatives 60 in the R for a methyl group or a phenyl or of acrylic acid amide, glycidyl acrylates and the like by straight-chain or branched alkyl groups Compounds with other olefinically unsaturated phenyl substituted with 1 to 18 carbon atoms Copolymerized with monomers. Under the influence group is, and in which η is an integer from 1 to 200, of heat and / or acidic catalysts can preferably 4 to 60, means, optionally in the aforementioned copolymers in a crosslinked mixture with known emulsifiers and / insoluble products are transferred. It has become or protective colloids at a pH between however, it has been shown that the above-mentioned mixed poly- 3 and 9 and temperatures of 20 to 90 ° C polymer- merisate has often already been pre-examined to a considerable extent.